Just for the record, I’ve managed to remove the erring files, within Hollywood Blvd, as below:-
1. Load DAZ (4.5 for me) in your usual way.
2. Select the Smart Content and Content Library tabs.
3. In the Smart Content tab, select Files in the top left-hand corner, then Unassigned in the left-hand column (the last item in the list for me). This should display all your .duf files, regardless of their location - I put my scene files in a suite of Render folders in my Content folder. You can tell which are your target files for deletion as they have a strident blap symbol displayed and/or a faded blue icon (what it is escapes me!).
4. If you are uncertain as to whether any file is an orphan, then attempt to Merge it into your blank scene pane. If it merges, then this is not an orphan file; if DAZ tells you that it can’t find a .duf file then this one is an orphan for deletion. Press OK to remove the warning message. If it wasn’t marked with that strident blap, then it will be now!
5. Now go to the Content Library tab. Shift the slider to the far left to where DAZ Studio Formats is high-lighted.
6. From your Smart Content tab, note the title of your first scene marked with a blap, and enter that title in the “Enter text to filter by…” box. Press Enter.
7. A magnifying glass symbol followed Search: Title of the scene should now be displayed and, in the pane below, the icon for the file you want to delete. If it isn’t there, then you did not enter the EXACT title from Smart Content tab ... or, like me, you need a new pair of specs!
8. If it is there, then right click it. “Remove Orphaned Reference” should be included in the options displayed.
9. Click it. It will seem as though nothing has happened, as the orphan will still be displayed in the Smart Content. To remove it you must either re-start DAZ or, for a less drastic option, select another set displayed in the Smart Content tab, e.g. Lights and then reselect Unassigned. The orphan will now be gone.
Now, how do we correctly remove an unwanted scene without leaving an orphan behind?